The development and implementation of Automatic Dependent Surveillance-Broadcast (ADS-B) technology around the world is expected to provide more operationally efficient airspace. In this environment, aircraft would be able to change their flight level during cruise in oceanic and procedural airspace for optimum flight level for better fuel consumption (better airplane performance), favorable winds (e.g. better tail wind), to avoid turbulence or due to presence of weather at the current flight level, and for other reasons.
During the cruise phase of a flight, the range on a navigation display (ND) is generally set by the flight crew to a much higher range than during other phases of flight, such as approach and departure from an airport or other air traffic congested area. At these high display ranges, displaying all the aircraft traffic can cause clutter and make it difficult and cumbersome for the flight crew to determine which aircraft traffic is of concern without evaluating each aircraft individually. This may involve evaluating a current altitude, range, direction of travel, vertical trend and other flight data provided for each aircraft. If all of the traffic is displayed on a display, such as a Vertical Situational Display (VSD) or other air traffic display device or system, the display of large numbers of aircraft in the vicinity can represent a significant work load for the flight crew. Additionally, such displays generally occupy a relatively small limited space on a cockpit display panel which can exacerbate efficient evaluation by the flight crew of the aircraft traffic situation around their own aircraft.